Date: Wed, 5 Mar 2008 15:46:53 -0800
From: Greg KH <greg@kroah.com>
To: Adrian McMenamin <lkmladrian@gmail.com>
Cc: LKML <linux-kernel@vger.kernel.org>, linux-sh <linux-sh@vger.kernel.org>
Subject: Re: Behaviour of device_register
Message-ID: <20080305234653.GA5904@kroah.com>
References: <8b67d60803051525g3aca775dmc14d1c2450b34168@mail.gmail.com>
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On Wed, Mar 05, 2008 at 11:25:48PM +0000, Adrian McMenamin wrote:
> The observed behaviour for me is that it appears to be blocking the
> vblank interrupt on my box (or more accurately stopping the workqueue
> that the interrupt handler calls from running). And without the vblank
> my bus won't process dma and so therefore the attempt to register the
> device in question fails.
> 
> But I can see no reason from a glance over the code why that (vblanks
> being blocked) would be the case - have I missed something and the
> vblanks will be blocked, or should I be looking elsewhere for the root
> cause of this problem?

device_register(), on it's own, does not touch any hardware, nor prevent
anything else in the kernel from happening.

So I think you need to look elsewhere, like into the bus that is doing
the device_register() call :)

good luck,

greg k-h
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